Repair of cylinder notch?


December 22, 2012, 10:24 PM
Is there a way to repair a cylinder with a damaged notch on the tapered edge? It locks up firmly when I do the usual trigger pull check, but without the trigger pulled the cylinder can be turned freely to the previous chamber.

I can't see investing a lot of money in it, but I'd like it to be repaired properly because it is after all a fairly old 5 screw from the 40's that's been in the family for a while.


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December 23, 2012, 08:38 AM

It really depends on how bad it`s peened , pics ?? make?? model ?? blued??SS??

Check the latch spring, it may be getting weak & not returning to full lock fast enuff , it also may be battered a bit .

To be on the safe side, I`d say replace it .

2 ways this happens , alot of dry firing or abusive/fast DA shooting.

Ruined a Python with the abusive shooting , the bluing never matched after cyl replacement :banghead: I was a big DUMMY when younger !!

Old Fuff
December 23, 2012, 10:03 AM
Without knowing exactly what revolver you have this is speculation, but your problem may be caused by a weak cylinder stop spring, and/or the ball on the cylinder stop (the part of it that sticks up through the frame and goes into the notch) isn't coming up high enough. Both issues are easy and inexpensive to fix.

December 23, 2012, 10:06 AM
Are you sure there's damage to the tapered edge of the notch? It's the other edge that normally gets the beating from abusive DA shooting. And the leading edge of the bolt can get a bit beat up, too, so check the bolt for a burr - if one developed, it may be preventing it from seating, in which case, you'd be able to turn the cylinder back, as you described. Matter of fact, check both edges of the slot and bolt for burrs. You may not need a new cylinder.

FWIW, not all fast DA shooting is "abusive". Largely depends on the shooter. Herky jerky trigger pulls are what do the damage. One can shoot very fast DA, but it pays to be smooth & consistent as well.

December 23, 2012, 03:21 PM
1940's S&W M&P, blued. Yes I'm pretty sure of what the problem is. The other cylinders hold without a problem. I'll try to post a photo so someone can tell me how bad it is.

I'd really rather not replace a number matched cylinder if there's any way to repair it. Thanks. (

December 23, 2012, 04:59 PM
I don't see any major bad problem there.

I'm betting on a weak or gummed up cylinder stop spring like Old Fuff said.


December 23, 2012, 05:25 PM
I'm sorry to disagree but I definitely see something wrong. If you can excuse my ignorance of terminology, that shiny area on the edge of the dished section is where the corner has been knocked off of the notch. I drew a green cross section with a red line showing how the metal has been knocked down. There isn't much left to prevent backward rotation.

I'll try replacing the cylinder stop though. I hope that fixes it. (

Old Fuff
December 23, 2012, 08:36 PM
The top of the cylinder stop ball in slanted to match the radius of the cylinder. On the leed side of the notch where the damage has occured the cause may be that the stop isn't going up far enough so there is only a small amount of engagement and the wear you see is the result. Try the following, or take the revolver to a gunsmith with a printed copy of this thread. Very good photographs by the way.

Remove the sideplate and mainspring. Turn the cylinder so that the cylinder stop in in the damaged notch. Then place the tip of a small screwdriver under the cylinder stop and force it into full engagement and block it there, so that when you attempt to turn the cylinder it can't cam the cylinder stop downward. Now, with the screwdriver/wedge in place see if you can turn the cylinder out of engagement. If not there is hope and when we know more I will continue.

December 23, 2012, 08:48 PM
send to smith repair service in texas

December 23, 2012, 10:06 PM
It's only a cell camera but thanks. A new cylinder stop spring and rod made no difference and shimming the spring helped a bit but not enough. Wedging the stop does keep the cylinder from turning, but I can't see the internal parts applying enough force to do that.

Here's a photo of the cylinder stop. It's a little worn on the side that normally engage the notches, but this side which prevents this backward rotation looks fine.

December 23, 2012, 10:34 PM
Check if the slot in the frame is battered sideways by the stop.

If it is, it may allow the stop to twist sideways and slip out of the notch.

A oversize stop could help with that, but has to be fitted to the cylinder notches while leaving the "oversize" oversize where it is inside the worn frame notch.

Or the slot can be peened to close it up, if you can devise the means to support it from the inside with a steel "anvil", and hit it from the outside with a steel "punch" to peen it.


December 23, 2012, 11:11 PM
Good call. I was wondering about the slop helping it slip out. The slot looks okay, but do you see what I do here?

The edges of the cylinder stop look pretty good, but it's not supposed to be thinner below the exposed portion is it? Hopefully a new cylinder stop fixes that.

December 23, 2012, 11:26 PM
I've been told this is a transitional pre-10 M&P.

Looks like I need this part:

instead of this one?

Old Fuff
December 23, 2012, 11:26 PM
Wedging the stop does keep the cylinder from turning, but I can't see the internal parts applying enough force to do that.

All that did was tell me that enough notch is left to hold. The next step would be to inspect the notch as explained by rcmodel.

In the picture I can't see if the other side of the cylinder stop ball is damaged by having the edge on the ball rounded off, but you should be able to tell.

Also at this point remove the screw in the front of the trigger guard and then remove the spring and plunger. An old dental pick works great if you have to catch and pull the spring out. You may have old grease in the hole. Clean it out with a pipe cleaner or Q-tip using a grease solvent and at the same time do the spring and plunger.

More later...

December 24, 2012, 12:14 AM
Neither of the edges appear to be rounded off, and yes the spring and its bore are very clean.

Is the cylinder stop supposed to like that in the last photo I posted? That amount of slop can't help matters any.

Thanks again for all the help.

December 24, 2012, 12:24 AM
I don't know if this is any help but on a SA gun I own, I took some material off the top of the bolt so it would rise a bit further. Worked like a charm and the gun locks up probably better than ever.

December 24, 2012, 04:01 AM
Looks like the effects of gangster slamming the cylinder home while spiinning it around fast. LIke they do in the movies. I have no idea if someone could TIG weld this or not then mill the notch back into the cylinder? No cheap fix! Too bad, some collector value.

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